Phantom: Privacy-Preserving Deep Neural Network Model Obfuscation in Heterogeneous TEE and GPU System

In this work, we present Phantom, a novel privacy-preserving framework for obfuscating deep neural network (DNN) model deployed in heterogeneous TEE/GPU systems. Phantom employs reinforcement learning to add lightweight obfuscation layers, degrading model performance for adversaries while maintaining functionality for authorized user. To reduce the off-chip data communication between TEE and GPU, we propose a Top-K layer-wise obfuscation sensitivity analysis method. Extensive experiments demonstrate Phantom's superiority over state-of-the-art (SoTA) defense methods against model stealing and fine-tuning attacks across various architectures and datasets. It reduces unauthorized accuracy to near-random guessing (e.g., 10% for CIFAR-10 tasks, 1% for CIFAR-100 tasks) and achieves a 6.99% average attack success rate for model stealing, significantly outperforming SoTA competing methods. System implementation on Intel SGX2 and NVIDIA GPU heterogeneous system achieves 35% end-to-end latency reduction compared with most recent SoTA work.